title: Ultrathin sP(EO-stat-PO) hydrogel coatings are biocompatible and preserve functionality of surface bound growth factors in vivo.
abstract: Hydrogel coatings prepared from reactive star shaped polyethylene oxide based prepolymers (NCO-sP(EO-stat-PO)) minimize unspecific protein adsorption in vitro, while proteins immobilized on NCO-sP(EO-stat-PO) coatings retain their structure and biological function. The aim of the present study was to assess biocompatibility and the effect on early osseointegrative properties of a NCO-sP(EO-stat-PO) coating with additional RGD-peptides and augmentation with bone morphogenetic protein-4 (BMP) used on a medical grade high-density polyethylene (HDPE) base under in vivo circumstances. For testing of biocompatibility dishes with large amounts of bulk NCO-sP(EO-stat-PO) were implanted subcutaneously into 14 Wistar rats. In a second set-up functionalization of implants with ultrathin surface layers by coating ammonia-plasma treated HDPE with NCO-sP(EO-stat-PO), functionalization with linear RGD-peptides, and augmentation with RGD and BMP-4 was analyzed. Therefore, implants were placed subcutaneously in the paravertebral tissue and transcortically in the distal femur of another 14 Wistar rats. Both tests revealed no signs of enhanced inflammation of the surrounding tissue analyzed by CD68, IL-1ß-/TNF-α-antibody staining, nor systemic toxic reactions according to histological analysis of various organs. The mean thickness of the fibrous tissue surrounding the femoral implants was highest in native HDPE-implants and tended to be lower in all NCO-sP(EO-stat-PO) modified implants. Micro-CT analysis revealed a significant increase of peri-implant bone volume in RGD/BMP-4 coated samples. These results demonstrate that even very low amounts of surface bound growth factors do have significant effects when immobilized in an environment that retains their biological function. Hence, NCO-sP(EO-stat-PO)-coatings could offer an attractive platform to improve integration of orthopedic implants.
authors.affiliation: Department of Orthopaedics, University of Ulm, Ulm, Germany.
authors.forename: Carl
authors.initials: C
authors.lastname: Neuerburg
authors.forename: Stefan
authors.initials: S
authors.lastname: Recknagel
authors.forename: Jörg
authors.initials: J
authors.lastname: Fiedler
authors.forename: Jürgen
authors.initials: J
authors.lastname: Groll
authors.forename: Martin
authors.initials: M
authors.lastname: Moeller
authors.forename: Kristina
authors.initials: K
authors.lastname: Bruellhoff
authors.forename: Heiko
authors.initials: H
authors.lastname: Reichel
authors.forename: Anita
authors.initials: A
authors.lastname: Ignatius
authors.forename: Rolf E
authors.initials: RE
authors.lastname: Brenner
mesh_terms: D000327:Adsorption; D000818:Animals; D015703:Antigens, CD / Q000378:metabolism; D015214:Antigens, Differentiation, Myelomonocytic / Q000378:metabolism; D055415:Bone Morphogenetic Protein 4 / Q000737:chemistry; D002448:Cell Adhesion; D020099:Coated Materials, Biocompatible / Q000737:chemistry*; D005269:Femur / Q000473:pathology; D020100:Hydrogels / Q000737:chemistry*; D036341:Intercellular Signaling Peptides and Proteins / Q000378:metabolism; D053583:Interleukin-1beta / Q000378:metabolism; D009842:Oligopeptides / Q000737:chemistry*; D016348:Osseointegration; D011092:Polyethylene Glycols / Q000737:chemistry*; D019736:Prostheses and Implants; D051381:Rats; D017208:Rats, Wistar; D013499:Surface Properties; D013997:Time Factors; D055114:X-Ray Microtomography; D000097382:CD68 Molecule
chemical_list: D015703:Antigens, CD; D015214:Antigens, Differentiation, Myelomonocytic; D055415:Bone Morphogenetic Protein 4; D020099:Coated Materials, Biocompatible; D020100:Hydrogels; D036341:Intercellular Signaling Peptides and Proteins; D053583:Interleukin-1beta; D009842:Oligopeptides; D011092:Polyethylene Glycols; C067980:CD68 antigen, human; D000097382:CD68 Molecule; C047981:arginyl-glycyl-aspartic acid